Method for detecting forensic evidence

ABSTRACT

A semiconductor forensic light is disclosed. The forensic light may use a variety of semiconductor light sources to produce light that contrasts forensic evidence against its background for viewing, photographing and collection. Example semiconductor light sources for the forensic light include light emitting diodes and laser chips. A heat sink, thermoelectric cooler and fan may be included to keep the forensic light cool. A removable light source head may be included on the forensic light to provide for head swapping to give the user access to different wavelengths of light.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] Priority is claimed to U.S. Provisional Patent Application SerialNo. 60/435,526 filed on Dec. 20, 2002.

BACKGROUND

[0002] In the field of forensic science, there is a need for a way todetect various evidence that may be used in a criminal prosecution,including blood, saliva, other body fluids, hair, flesh, bone fragments,teeth, human skin damage such as bruises, bite marks or cuts, shoeprints, fingerprints, footprints, tire prints, gunpowder residue,bullets and portions thereof, explosive devices, explosive materials,parts of explosives, chemical weapons, chemical agents, biologicalweapons, paint, grease or oil, glass fragments, metal rubbings, fibers,dust patterns, various trace evidence, alteration of documents (forgery,different inks), narcotics, herbal evidence, and components, residuesand traces thereof.

[0003] In the past, forensic personnel used high intensity conventionallight sources, such as halogen bulbs, or ion gas laser light sources inorder to illuminate areas of a crime scene and attempt to detectevidence since some evidence such as fingerprints do not fluorescencebrightly alone. Contrast between such evidence being sought and thebackground against which it was found was sometimes achieved by usingfluorescent dusting powder, dye, or other marker material, and lighthaving a wavelength that substantially coincides with a known excitationwavelength of the marker. The characteristic of the marker is that, uponillumination with light at one of its excitation wavelengths, it willfluoresce, or emit light. Such fluorescence is typically at a longerwavelength as compared to the excitation wavelength. Examination ofevidence was also enhanced through the use of color filtering glasses orbarrier filters, whose color filtering characteristics are tuned tomaximize the image to be detected. The forensic lights in the past hadnumerous drawbacks including bulky size, need for access to an AC powersupply, and high cost.

SUMMARY

[0004] Various structures and components of a forensic light that uses asemiconductor light sources are disclosed.

DETAILED DESCRIPTION

[0005] Referring to FIG. 1, an example forensic light 100 is depicted.It includes a housing 101 that houses various components of the forensiclight, such as control circuitry and the battery pack. On the top of thehousing 101, there is a power level selection button 103 for selectingfull power in different level, and display lights (such as LED indicatorlights) for indicating power level of light operation. Different powerlevel operations may be needed for different detection purposes.Optionally, a tripod mounting attachment mechanism for camera use may beincluded. On the bottom of the housing there is a trigger 102 forinitiating and terminating light output from the forensic light. Sincethe forensic light produces light of an intensity that can damage thehuman eye, a spring loaded trigger may be provided so that if a user isnot actively soliciting light output by squeezing the trigger, output oflight from the forensic light will cease. A battery pack or a power pack105 may be included at the proximal end of the housing or main lightbody. The light can be operated by battery if the battery pack is usedand the light can be operated by AC power using a switching power supplyor by use of an automobile DC adaptor when a power pack is used. A lighthead 106 may be provided at the distal end of the housing or main lightbody that may be removable from the housing 101 or main body of theforensic light. The light head 106 may contain the light source andother components. Since the light source produces heat as well as light,it may be desirable to include ventilation apertures 108 that permit airto enter the light head to provide a cooling effect. Additionally, airexit vents 107 are provided for air circulation through the light head.Light beams will exit the light head at the exit aperture 109 which mayinclude a protective cover to prevent dirt or moisture from damaging thelight source and which may also protect the light source from mechanicaldamage. In the light head, an adapter 111 may be included to permitviewing of forensic evidence through filters, focusing lenses, diffusersand polarizers.

[0006] Referring to FIG. 2a, if it is desired to have a battery-operatedforensic light, then a battery charger 201 may be provided. The batterycharger may include a body 202 with a periphery on which a receptacle203 may be provided for receiving electrical power. A battery receptacle204 may be provided for receiving batteries or a power pack forcharging. The battery used in the light operation is embedded in abattery pack. The battery charger can be operated by a AC power or anautomobile DC adapter power supply.

[0007] Referring to FIG. 2b, an example battery pack or power pack 210is depicted. The battery pack 210 may include a plastic casing 205, abase 205, a lock 208 and an electrical contact 208.

[0008] Referring to FIG. 3, a power pack unit 301 may be provided foroperating the forensic light. The power pack 301 includes an AC powersupply and plug 302 to receive AC power and convert it to DC power, acable or wire 303 to conduct electrical power, and a plug 304 to connectthe cable to the power pack 305. There is an electrical connection 306for the power pack to contact electronic circuitry within the forensiclight. The physical configuration of the power pack 305 is the same asbattery pack so that the light unit can be operated by either batterypack or AC power using a power pack.

[0009] Referring to FIG. 4, a provision has been made to operate theforensic light by use of a DC adapter. This allows for convenient use ofthe forensic light in an automobile. The DC adaptor 401 has a DC plug402 to fit into universal DC outlet such as found in an automobile, acable or wire 403 to conduct power, and a plug 404 to connect the DCadapter to a power pack such as that depicted in FIG. 3.

[0010] By assembling a kit of the foregoing components, a forensic lightkit may be provided that is powered by a battery pack, AC power or DCpower, at the user's discretion. Such a kit may include other componentssuch as the light heads of different wavelengths disclosed below andother desired hardware such as filters, glasses, etc.

[0011] Referring to FIG. 5, a cross sectional view of the forensic light100 of FIG. 1 is depicted. Control circuitry 501 is provided forcontrolling operation of the light. The control circuitry controls theon/off function of the forensic light as well as light intensity.Electrical connections 502 are provided for establishing electricalcontact between the main light body and the removable light head. Thecontrol circuitry is also connected to the power supply (either batterypack or power pack as described above) through connection 503. A fan 504may be provided within the light head for air circulation and heatdissipation. Individual semiconductor light producing devices 505 suchas light emitting diode (LED) modules (including LED chip mounted on aprimary heat sink and covered by a cover or plastic dome) or laser chipsare mounted on the distal side of a thermoelectric (“TE”) cooler 507which is affixed to a secondary heat sink 508 that dissipates most ofthe heat produced by the light producing devices. The semiconductorlight producing devices may be mounted to a heat sink by heat conductiveadhesive 509. The TE cooler is optional and may be used in someapplications. The proximal side of the secondary heat sink 508 has afinned or comb-shaped wings to increase the surface area of thesecondary heat sink in order to increase contact of the heat sink withair and improve heat dissipation. Air from the fan moves past thesecondary heat sink for heat dissipation. A light reflector 510 such asa conical or parabolic reflector may be provided to collect light fromthe semiconductor light producing devices and direct it through a lightexit aperture 109 and/or cover or focus lens to produce useful lightbeams 511. An optional protective cover or focus lens 512 may beincluded at the light exit to protect electronic components from dirtand physical damage. If a focus lens is used, it can be used toconcentrate the light beam and determine a desired light footprint. Thenumber of semiconductor light producing devices can vary from 1 to anydesired number based on the power levels desired in the forensic light.

[0012]FIG. 6 depicts a side view of an LED module 600 according to aflip-chip design that can serve as a light source for a forensic light.The light source 600 includes a cover or dome 601 that serves to protectthe LED(s) within from contamination from moisture and dirt and frommechanical damage. The dome 601 may also serve to focus light emitted bythe LED. A light emitting diode chip array 607 is mounted in invertedposition in a well 606 of a heat sink 605 according to the so-called‘flip chip’ design. In this example, the chip has an insulativesubstrate. The chip 607 is mounted on a flip chip pad 608 within thewell 606. Electrode beads or bumps 607 a and 607 b separate the chipfrom the pad but attach the chip to the pad and provide electricalconnection. The pad is affixed to the bottom of the well by a methodsuch as soldering, brazing, welding or use of a heat-conductive adhesive605. The chip has an electrode on top and its epitaxial layers(semiconductor material) facing down toward the pad and the bottom ofthe well in the figure. The pad upper surface may be light reflective sothat light is reflected from the pad in a useful direction. The pad maybe coated with a light reflective film, such as Au, Al or Ag. The heatsink may be surrounded by an insulative jacket 603. The chip is poweredvia wires 609 a and 609 b attached to intermediate islands 604 a and 604b which are in turn contacted by wires 602 a and 602 b. Light from thelight source is emitted as a beam 610 having an angle of departure θthat is defined and determined in part by the angle of the walls of thewell as well as by any focusing or restrictive characteristics of thedome. In such a package, all of the light emitted from the chip can bereflected back in the light exit direction for highest light output. Thewell may also include a reflective coating or polished surface.

[0013]FIG. 7 depicts an LED module 700 that includes a well 706 within aheat sink 705 and having a plurality or array of LED chips 707 a, 707 b,707 c, etc. within the well. The depth of the well can be from 0 mm tomore than 50 mm. Each individual LED chip may include semiconductormaterial or epitaxial layers 709 a on a substrate 709 b. Each chip maybe mounted to the heat sink by use of heat conductive adhesive or othermounting means. The chips in this figure are wired in series, althoughwiring in parallel is also possible when the application requires it.The remainder of the features of the LED 700 module are similar to thosealready discussed.

[0014]FIG. 8 depicts a semiconductor light emitting module 800 that hasa single LED or laser chip 807 mounted in a well 806 of a heat sink 805.The chip 807 has a conductive substrate and may be mounted to the floorof the well of the heat sink by use of a heat conductive adhesive. Thedepth of the well can be from 0 mm to more than 50 mm. The chip ispowered by wire 809 from island 803. A wire lead 802 a brings electricalpower to the module. An insulative jacket 804 may be placed around theheat sink for electrical insulation. A negative electrode 802 isprovided on the bottom of the heat sink for electrical conduction.

[0015]FIG. 9 depicts an LED module 900 that includes an array ofsemiconductor light producing chips 907 a, 907 b, etc. within a well ofa heat sink. The chips use an electrically conductive substrate andthere is a negative electrode 901 on the heat sink for electricalconnection.

[0016] For forensic light sources with multiple semiconductor lightproducing chips, the quantity of chips used may vary depending onapplication, and can range from 1 to several hundred. The spacingbetween chips can be adjusted from zero to more than 1 mm, depending onthe application requirements. The semiconductor chip producing light maybe a single chip or single chip array. The chip or chips may be mountedin a well of a heat sink or may be mounted directly on a heat sink. Thewavelength of light emitted from each chip in a multi-chip forensiclight design may be the same wavelength or different wavelengths tocover a desired light spectral range. If a well is provided in the heatsink, the depth of the well may be as desired, such as from 0 to 50 mmor more, depending on application.

[0017] The forensic light source may be constructed with the chip(s)mounted to the primary heat sink, such as by use of a heat conductiveand/or light reflective adhesive. The primary heat sink can be attachedto a secondary heat sink if desired, such as by use of a heat conductiveand/or electrically insulative adhesive, welding, brazing, soldering ormechanical fixation.

[0018] The chip(s) may be any of those described herein or otherwise,such as a flip chip design. The primary heat sink, chip(s) and dome canbe combined as a light module. A cover may be provided over the dome. Anexample cover would include a plastic fitting or attachment and a glasswindow through which light may travel. Glass generally has better lighttransmission qualities than plastic, but either could be used. The domecan serve as a focusing lens.

[0019] A reflective cone may be included in the forensic light, such asbetween the dome and the light exit or apeture from which light exitsthe forensic light. The cone can be used for a light conservationpurpose, to capture and use light that would be errant and wouldotherwise be wasted. The cone can also be used for the purpose of beamshaping and to create a light beam with a desired footprint. Examplelight beam footprints include circular, oval, square, rectangular, andany other geometric shape, depending on application. The footprint canbe any desired size for the application. A shaped beam can have superiorlight intensity. The reflective cone can have an interior surface thatreflects light. Some cones may reflect at least as much as 85% of thelight that encounters them. Materials of cones can be plastic or metal,polished or plated metal such as aluminum or alloy, or otherwise. Use ofa cone allows superior maintenance of light beam intensity as distancefrom the chip(s) increases.

[0020] Heat sinks are often a combination of two different kinds ofmaterials, the first with a low thermal expansion rate and the secondwith high thermal conductivity. Monolithic heat sinks may be used aswell. Examples of some heat sink materials which may be used in lightsdepicted herein include metals, copper, aluminum, silver, magnesium,steel, silicon carbide, boron nitride, tungsten, molybdenum, cobalt,chrome, Si, SiO₂, SiC, AlSi, AlSiC, natural diamond, monocrystallinediamond, polycrystalline diamond, polycrystalline diamond compacts,diamond deposited through chemical vapor deposition and diamonddeposited through physical vapor deposition, and composite materials orcompounds. Any materials with adequate heat conductance and/ordissipation properties can be used. If desired, a heat sink may havefins or other surface modifications or structures to increase surfacearea or promote air flow and enhance heat dissipation.

[0021] Examples of heat conductive and/or electrically insulativeadhesives that may be used are silver based epoxy, other epoxies, andother adhesives with a heat conductive quality and/or electricallyinsulative quality. In order to perform a heat conductive function, itis important that the adhesive possess the following characteristics:(i) strong bonding between the materials being bonded, (ii) adequateheat conductance, (iii) electrically insulative or electricallyconductive if desired (or both), and (iv) light reflectivity if desired,or any combination of the above. Examples of light reflective adhesiveswhich may be used to affix chips to a heat sink include silver andaluminum based epoxy. One example heat conductive and electricallyinsulative adhesive includes a mixture of a primer and an activator. Inthis example, the primer may contain one or more heat conductive agentssuch as aluminum oxide (about 20-60%) and/or aluminum hydroxide (about15-50%). The primer may also contain one or more bonding agents such aspolyurethane methacrylate (about 8-15%), and/or hydroxyalkylmethacrylate (about 8-15%). An activator may be mixed with the primer toform an adhesive. The activator may include any desired catalyst, forexample n-heptane (about 5-50%), aldheyde-aniline condensate (about30-35%), isopropyl alcohol (about 15-20%), and an organocopper compound(about 0.01 to 0.1%). Adhesives such as described herein can be used tomount a chip to a primary heat sink, or to mount a primary heat sink toa secondary heat sink, or both.

[0022] Examples of substrates on which the semiconductors used in theforensic lights depicted herein may be grown include Si, GaAs, GaN, ZnS,ZnSe, InP, Al₂O₃, SiC, GaSb, InAs and others. Both electricallyinsulative and electrically conductive substrates may be used.

[0023] Epitaxial layers and structures of semiconductor light emittingchips useful in forensic lights disclosed herein may include a substrate(such as sapphire) that serves as a carrier pad or platform on which togrow the chip's epitaxial layers. The first layer placed on thesubstrate may be a buffer layer (such as a GaN buffer layer). Use of abuffer layer reduces defects in the chip that would otherwise arise dueto differences in material properties between the epitaxial layers andthe substrate. Then a contact layer, such as n−GaN, may be provided. Acladding layer such as n−AlGaN Sub may be present to confine injectedelectrons. An active layer may be provided to emit the light whenexcited by electrons. An example active layer is such as InGaN withmultiple quantum wells. The active layer is where electrons jump from aconduction band to valance and emit energy which converts to light. Onthe active layer, another cladding layer may be provided, such asp−AlGaN, to serve to confine electrons. A contact layer such as p+GaNmay be provided that is doped for Ohmic contact. The contact layer mayhave an electrode mounted on it.

[0024] The physical dimension of the chip(s), including their surfacearea, used in the forensic light can impact the intensity of the lightproduced. The chips could be of any desired size and shape, and mightrange from a surface area of more than about 300 um. Each individualchip may have a power output more than about 20 mW. The chips may emitlight of any desired wavelength, including light from wavelengthsranging from 200 to 1500 nm.

[0025] Some examples of semiconductor light sources which may be desiredto be used in a forensic light include light emitting diode chips, LEDchip arrays (an LED chip with a large surface area and having paths ofelectrically conductive material projecting across some portions of itssurface to power the chip), laser diodes, vertical cavity surfaceemitting laser, edge emitting lasers, surface emitting lasers, andothers.

[0026] Example material which may be used in the TE cooler includeinclude Bi₂Te₃, PbTe, SiGe, BeO₂, BiTeSe, BiTeSb, AlO₃, AlN, BaN andothers.

[0027] Heat sinks used in the lights can be of a variety of shapes anddimensions, such as those depicted in the drawings or any others whichare useful for the structure of the particular light source beingconstructed. It should be noted that the heat sink arrangement should besufficient to prevent overheating of the semiconductor light source, ordiminished light production and shortened product life may result.

[0028] A user of the forensic light will find it advantageous to selecta light output frequency centered around a wavelength that tends tocontrast the evidence being searched for against its backgroundmaterial. A table is provided below suggesting some wavelengths that maybe desired for detecting various substances. Quick detachable lightsources or heads for the forensic light may be manufactured that produceeach of these specific wavelengths so that the forensic light user has akit available with an array of different light sources available. ColorSubstance UV (<400 nm) Fingerprints Near UV (405 nm) human skin damagesuch as bruises, bite marks or cuts Blue (450 nm) blood, saliva, otherbody fluids, hair, flesh, bone fragments Green (525 nm) shoe prints,fingerprints, footprints, tire prints, paint, grease or oil, glassfragments, metal rubbings, fibers, dust patterns, various trace evidenceYellow (590 nm) gunpowder residue, bullets, explosive materials Red (630nm) alteration of documents (forgery), narcotics, herbal evidenceInfrared(>800 nm) Document examination

[0029] As desired, the forensic light may be configured to produce lightthat centers around a single wavelength, or multiple removable lightsources capable of producing light of different wavelengths may beproduced so that the user may select a light source of the appropriatewavelength for his application. In addition, if desired the forensic thelight may be structured so that the user may select a light output powerlevel that is less than full power output. For example, the forensiclight may be structured so that the user may select a light output powerlevel of ¼, ½, ¾ or full light output power. An example of light poweroutput in milliwatts (mW) at those example levels for light centered onfive (5) different wavelengths is shown in the table below. ¼ ½ ¾ FullColor power power power power UV (405 nm) 100 200 300 400 Blue (450 nm)250 500 750 1000 Green (525 nm) 200 400 600 800 Yellow (590 nm) 100 200300 400 Red (630 nm) 100 200 300 400

[0030] It is possible for the forensic light to output light at any of avariety of different wavelengths, including but not limited to 280 nm,350 nm, 400 nm, 405 nm, 450 nm, 525 nm, 590 nm, 630 nm, 800 nm, 980 nm,1064 nm, 1300 nm and 1500 nm. Power output levels could be from lessthan 1 mW to more than 9000 mW.

[0031] The advantage of being able to produce light at less than thefull light output power level is to provide contract against evidencebackground in different environment. It is also possible to produceforensic lights that have a fixed intensity power output. The forensiclight may be used to fluoresce or illuminate evidence, to contrast itwith a background, to fluoresce or illuminate the background to contrastit with evidence, or to otherwise use light in detecting the presence ofevidence.

[0032] Some other advantageous features that the forensic light mayinclude are discussed here. Portability is one such feature. Theforensic light may be configured as a hand-held, battery-operated devicethat may be used at remote locations and may be easily transported andeasily stored. The forensic light may be adaptable to other equipmentsuch as a camera or image intensifying devices. The forensic light maybe configured as a ring light that attaches to the font end of a cameralens and or image intensifying device thereby providing evenilluminations of the desired field. In such a configuration the ringlight could be constructed to accept filters, allowing the device to beremoved from the equipment and used to view evidence directly in thesame manner that a handheld magnifying glass would be used.Additionally, the forensic light may be configured to accept filtersthat positioned at the light output point intended to manipulate theoutput. Such filters could be a diffuser to soften or defocus the lightbeing emitted, a focus lens to narrow the light beam intensifying thelight over a small area, narrowband pass for narrowing the wavelengthband being emitted, and or polarizing filter to plane polarize the lightbeing emitted. Such filters and lenses are readily and commerciallyavailable in a variety of sizes and shapes from several sources. Such aconfiguration would also allow the attachment of viewing filters andlenses for the user. The forensic light could be configured to acceptboth light output filters and lenses and viewing filters and lensessimultaneously. Another optional feature is a camera mount that allowsthe forensic light to be positioned with respect to a camera in order tophotograph forensic evidence. Forensic lights may also used to providelight in the non-visible spectra (such as the UV and IR ranges) thatreflects off the evidence and may be detected by a photon multiplierthat in turn projects the light and image onto a view screen.

[0033] A forensic light constructed according to principles disclosedherein may be used to carry out a method for locating or detectingforensic evidence. Such a method may be designed or intended to locatevarious types of forensic evidence or materials that may later be usedin a criminal prosecution, civil proceedings, or for other purposes.Examples of forensic evidence that a user of the forensic light maydesire to gather include but are not limited to blood, saliva, otherbody fluids, hair, flesh, bone fragments, teeth, human skin damage suchas bruises, bite marks or cuts, shoe prints, fingerprints, footprints,tire prints, gunpowder residue, bullets and portions thereof, explosivedevices, explosive materials, parts of explosives, chemical weapons,chemical agents, biological weapons, paint, grease or oil, glassfragments, metal rubbings, fibers, dust patterns, various traceevidence, alteration of documents (forgery, different inks), narcotics,herbal evidence, and components, residues and traces thereof.

[0034] The method can include the steps of:

[0035] determining a type or class of forensic evidence sought to bediscovered,

[0036] determining or selecting the wavelength of light that may beuseful in detecting such forensic evidence, such as by contrasting suchforensic evidence against its background,

[0037] obtaining, setting, building or modifying a semiconductorforensic light that outputs light of such wavelength,

[0038] illuminating a physical area with the light output by theforensic light in order to detect desired forensic evidence,

[0039] viewing any detected forensic evidence (viewing may take placethrough a filter, image intensifier if desired),

[0040] photograph the detected forensic evidence,

[0041] enhance or project any image of the evidence,

[0042] collect the detected forensic evidence, and

[0043] store the collected forensic evidence.

[0044] These method steps may be modified, steps may be omitted, orother steps may be added.

[0045] While the present lights have been described and illustrated inconjunction with a number of specific configurations, those skilled inthe art will appreciate that variations and modifications may be madewithout departing from the principles herein illustrated, described, andclaimed. The present invention, as defined by the appended claims, maybe embodied in other specific forms without departing from its spirit oressential characteristics. The configurations of lights described hereinare to be considered in all respects as only illustrative, and notrestrictive. All changes that come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

1. A method for detecting forensic evidence comprising: accessing asemiconductor forensic light that has a handle, a plurality of lightheads attachable to and detachable from said handle, each of said lightheads being capable of emitting a light of different wavelength thananother of said heads, at least one of said light heads including asemiconductor light emitting device that can emit light of a wavelengthuseful in detecting forensic evidence, and a primary heat sink to whichsaid semiconductor light emitting device is affixed, said primary heatsink serving to draw heat away from said semiconductor light emittingdevice, and at least one light exit on said light head, said light exitbeing sized and shaped to permit light to exit said light head for usein detecting forensic evidence, placing said semiconductor forensiclight in a physical location where forensic evidence is expected to bediscovered, actuating a switch on said handle to cause a light beam tobe emitted by said semiconductor forensic light, causing said light beamto shine on an area that may contain forensic evidence, observing acontrast between forensic evidence in said light beam and the backgroundwhere it rests.
 2. A method as recited in claim 1 further comprisingphotographing said forensic evidence.
 3. A method as recited in claim 1further comprising collecting said forensic evidence.
 4. A method asrecited in claim 1 wherein said forensic light further comprises: asecondary heat sink to which said primary heat sink is affixed, saidsecondary heat sink serving to dissipate heat produced by saidsemiconductor light emitting device, a thermoelectric cooler located onsaid secondary heat sink, said thermoelectric cooler experiencing a dropin temperature when subjected to a voltage, and a fan serving to moveair past said thermoelectric cooler in order to cool the light source,and at least one ventilation aperture on said light head for permittingair to enter and exit the light head to facilitating heat dissipation.5. A method as recited in claim 1 wherein said semiconductor lightproducing device is an LED module that include the primary heat sink, anLED chip located in a well on the primary heat sink, and a dome oversaid LED chip, the LED chip including a substrate and epitaxial layers;and further comprising the step of supplying electrical power to saidepitaxial layers in order to produce said light beam.
 6. A method asrecited in claim 1 wherein said forensic light further comprises a lightreflector in said light head for reflecting light from said light sourceout of said light head.
 7. A method as recited in claim 1 wherein saidheat sink includes a material selected from the group consisting ofcopper, aluminum, silver, magnesium, steel, silicon carbide, boronnitride, tungsten, molybdenum, cobalt, chrome, Si, SiO₂, SiC, AlSi,AlSiC, and diamond.
 8. A method as recited in claim 1 wherein saidsemiconductor light producing device includes epitaxial layers locatedon a substrate and wherein said substrate is selected from the groupconsisting of Si, GaAs, GaN, ZnS, ZnSe, InP, Al₂O₃, SiC, GaSb, and InAs.9. A method as recited in claim 1 wherein said semiconductor lightproducing device includes epitaxial layers located on a substrate, andat least one of the epitaxial layers is selected from the groupconsisting of: a buffer layer to reduce defects in the chip that mayarise due to differences in material properties between the epitaxiallayers and the substrate, a contact layer, a cladding layer serving toconfine injected electrons, and an active layer that emits the lightwhen excited by electrons, the light emitted being useful in forensicdetection of evidence; and further comprising: injecting electrons intosaid active layer, permitting said active layer to emit photons,permitting said photons to exit said semiconductor forensic light as alight beam.
 10. A method as recited in claim 9 wherein light emittedfrom said semiconductor light producing device is of a wavelength in therange of 200 to 1500 nm.
 11. A method as recited in claim 1 wherein saidlight beam has a color that is selected from the group consisting ofblue, green, yellow, red, infrared and ultraviolet.
 12. A method asrecited in claim 1 wherein said light beam has a wavelength centeredaround a wavelength selected from the group consisting of 405 nm, 450nm, 525 nm, 590 nm, and 630 nm.
 13. A method as recited in claim 1wherein said light beam is applied to forensic evidence selected fromthe group consisting of blood, saliva, other body fluids, hair, flesh,bone fragments, teeth, human skin damage such as bruises, bite marks,cuts, shoe prints, fingerprints, footprints, tire prints, gunpowderresidue, bullets and portions thereof, paint, grease, oil, glassfragments, metal rubbings, fibers, dust patterns, alteration ofdocuments, narcotics, and herbal evidence.
 14. A method as recited inclaim 1 wherein said light beam has an intensity within the range of 1mW to 9000 mW.
 15. A method for detecting forensic evidence comprising:accessing a semiconductor forensic light that has a semiconductor lightemitting device that can emit light of a wavelength useful in detectingforensic evidence, and a primary heat sink to which said semiconductorlight emitting device is affixed, said primary heat sink serving to drawheat away from said semiconductor light emitting device, and at leastone light exit, said light exit being sized and shaped to permit lightto exit said light head for use in detecting forensic evidence, placingsaid semiconductor forensic light in a physical location where forensicevidence is expected to be discovered, actuating a switch to cause alight beam to be emitted by said semiconductor forensic light, causingsaid light beam to shine on an area that may contain forensic evidence,observing a contrast between forensic evidence in said light beam andthe background where it rests.
 16. A method as recited in claim 15further comprising photographing said forensic evidence.
 17. A method asrecited in claim 15 further comprising collecting said forensicevidence.
 18. A method as recited in claim 16 wherein said forensiclight further comprises: a secondary heat sink to which said primaryheat sink is affixed, said secondary heat sink serving to dissipate heatproduced by said semiconductor light emitting device, a thermoelectriccooler located on said secondary heat sink, said thermoelectric coolerexperiencing a drop in temperature when subjected to a voltage, and afan serving to move air past said thermoelectric cooler in order to coolthe light source, and at least one ventilation aperture on said lighthead for permitting air to enter and exit the light head to facilitatingheat dissipation.
 19. A method as recited in claim 15 wherein saidforensic light further comprises: a secondary heat sink to which saidprimary heat sink is affixed, said secondary heat sink serving todissipate heat produced by said semiconductor light emitting device. 20.A method as recited in claim 15 wherein said semiconductor lightproducing device is an LED module that include the primary heat sink, anLED chip located in a well on the primary heat sink, and a dome oversaid LED chip, the LED chip including a substrate and epitaxial layers;and further comprising the step of supplying electrical power to saidepitaxial layers in order to produce said light beam.
 21. A method asrecited in claim 15 wherein said forensic light further comprises alight reflector in said light head for reflecting light from said lightsource out of said light head.
 22. A method as recited in claim 15wherein said semiconductor light producing device includes epitaxiallayers located on a substrate, and at least one of the epitaxial layersis selected from the group consisting of: a buffer layer to reducedefects in the chip that may arise due to differences in materialproperties between the epitaxial layers and the substrate, a contactlayer, a cladding layer serving to confine injected electrons, and anactive layer that emits the light when excited by electrons, the lightemitted being useful in forensic detection of evidence; and furthercomprising: injecting electrons into said active layer, permitting saidactive layer to emit photons, permitting said photons to exit saidsemiconductor forensic light as a light beam.
 23. A method as recited inclaim 15 wherein said light beam has a color that is selected from thegroup consisting of blue, green, yellow, red, infrared and ultraviolet.24. A method as recited in claim 15 wherein said light beam has awavelength centered around a wavelength selected from the groupconsisting of 405 nm, 450 nm, 525 nm, 590 nm, and 630 nm.
 25. A methodas recited in claim 15 wherein said light beam is applied to forensicevidence selected from the group consisting of blood, saliva, other bodyfluids, hair, flesh, bone fragments, teeth, human skin damage such asbruises, bite marks, cuts, shoe prints, fingerprints, footprints, tireprints, gunpowder residue, bullets and portions thereof, paint, grease,oil, glass fragments, metal rubbings, fibers, dust patterns, alterationof documents, narcotics, and herbal evidence.
 26. A method as recited inclaim 15 further comprising the step of utilizing a photon multiplierwhich in turn projects light and an image onto an view screen.